Cell C charges Cancelation fees if you don't upgrade

Cell C charge me cancelation fees after i didn't want to upgrade and served and PAID my full two years of my contract i tried to resolve it and even have a message with a reference number saying its been resolved yet i still get messages about the arrears payments i been on the phone for more then an hour trying to resolve it probably for the 5th time yet i get send from pillar to post kept hold on the line for 22min and i have proof of that im so tired of trying but no one helps and the consultants are rude treating you like your a ******** CAN SOMEONE PLEASE HELP ME